import {
Matrix4,
Vector2
} from 'three';
/**
* References:
* https://lettier.github.io/3d-game-shaders-for-beginners/screen-space-reflection.html
*/
const SSRShader = {
defines: {
MAX_STEP: 0,
PERSPECTIVE_CAMERA: true,
DISTANCE_ATTENUATION: true,
FRESNEL: true,
INFINITE_THICK: false,
SELECTIVE: false,
},
uniforms: {
'tDiffuse': { value: null },
'tNormal': { value: null },
'tMetalness': { value: null },
'tDepth': { value: null },
'cameraNear': { value: null },
'cameraFar': { value: null },
'resolution': { value: new Vector2() },
'cameraProjectionMatrix': { value: new Matrix4() },
'cameraInverseProjectionMatrix': { value: new Matrix4() },
'opacity': { value: .5 },
'maxDistance': { value: 180 },
'cameraRange': { value: 0 },
'thickness': { value: .018 }
},
vertexShader: /* glsl */`
varying vec2 vUv;
void main() {
vUv = uv;
gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );
}
`,
fragmentShader: /* glsl */`
// precision highp float;
precision highp sampler2D;
varying vec2 vUv;
uniform sampler2D tDepth;
uniform sampler2D tNormal;
uniform sampler2D tMetalness;
uniform sampler2D tDiffuse;
uniform float cameraRange;
uniform vec2 resolution;
uniform float opacity;
uniform float cameraNear;
uniform float cameraFar;
uniform float maxDistance;
uniform float thickness;
uniform mat4 cameraProjectionMatrix;
uniform mat4 cameraInverseProjectionMatrix;
#include <packing>
float pointToLineDistance(vec3 x0, vec3 x1, vec3 x2) {
//x0: point, x1: linePointA, x2: linePointB
//https://mathworld.wolfram.com/Point-LineDistance3-Dimensional.html
return length(cross(x0-x1,x0-x2))/length(x2-x1);
}
float pointPlaneDistance(vec3 point,vec3 planePoint,vec3 planeNormal){
// https://mathworld.wolfram.com/Point-PlaneDistance.html
//// https://en.wikipedia.org/wiki/Plane_(geometry)
//// http://paulbourke.net/geometry/pointlineplane/
float a=planeNormal.x,b=planeNormal.y,c=planeNormal.z;
float x0=point.x,y0=point.y,z0=point.z;
float x=planePoint.x,y=planePoint.y,z=planePoint.z;
float d=-(a*x+b*y+c*z);
float distance=(a*x0+b*y0+c*z0+d)/sqrt(a*a+b*b+c*c);
return distance;
}
float getDepth( const in vec2 uv ) {
return texture2D( tDepth, uv ).x;
}
float getViewZ( const in float depth ) {
#ifdef PERSPECTIVE_CAMERA
return perspectiveDepthToViewZ( depth, cameraNear, cameraFar );
#else
return orthographicDepthToViewZ( depth, cameraNear, cameraFar );
#endif
}
vec3 getViewPosition( const in vec2 uv, const in float depth/*clip space*/, const in float clipW ) {
vec4 clipPosition = vec4( ( vec3( uv, depth ) - 0.5 ) * 2.0, 1.0 );//ndc
clipPosition *= clipW; //clip
return ( cameraInverseProjectionMatrix * clipPosition ).xyz;//view
}
vec3 getViewNormal( const in vec2 uv ) {
return unpackRGBToNormal( texture2D( tNormal, uv ).xyz );
}
vec2 viewPositionToXY(vec3 viewPosition){
vec2 xy;
vec4 clip=cameraProjectionMatrix*vec4(viewPosition,1);
xy=clip.xy;//clip
float clipW=clip.w;
xy/=clipW;//NDC
xy=(xy+1.)/2.;//uv
xy*=resolution;//screen
return xy;
}
void main(){
#ifdef SELECTIVE
float metalness=texture2D(tMetalness,vUv).r;
if(metalness==0.) return;
#endif
float depth = getDepth( vUv );
float viewZ = getViewZ( depth );
if(-viewZ>=cameraFar) return;
float clipW = cameraProjectionMatrix[2][3] * viewZ+cameraProjectionMatrix[3][3];
vec3 viewPosition=getViewPosition( vUv, depth, clipW );
vec2 d0=gl_FragCoord.xy;
vec2 d1;
vec3 viewNormal=getViewNormal( vUv );
#ifdef PERSPECTIVE_CAMERA
vec3 viewIncidentDir=normalize(viewPosition);
vec3 viewReflectDir=reflect(viewIncidentDir,viewNormal);
#else
vec3 viewIncidentDir=vec3(0,0,-1);
vec3 viewReflectDir=reflect(viewIncidentDir,viewNormal);
#endif
float maxReflectRayLen=maxDistance/dot(-viewIncidentDir,viewNormal);
// dot(a,b)==length(a)*length(b)*cos(theta) // https://www.mathsisfun.com/algebra/vectors-dot-product.html
// if(a.isNormalized&&b.isNormalized) dot(a,b)==cos(theta)
// maxDistance/maxReflectRayLen=cos(theta)
// maxDistance/maxReflectRayLen==dot(a,b)
// maxReflectRayLen==maxDistance/dot(a,b)
vec3 d1viewPosition=viewPosition+viewReflectDir*maxReflectRayLen;
#ifdef PERSPECTIVE_CAMERA
if(d1viewPosition.z>-cameraNear){
//https://tutorial.math.lamar.edu/Classes/CalcIII/EqnsOfLines.aspx
float t=(-cameraNear-viewPosition.z)/viewReflectDir.z;
d1viewPosition=viewPosition+viewReflectDir*t;
}
#endif
d1=viewPositionToXY(d1viewPosition);
float totalLen=length(d1-d0);
float xLen=d1.x-d0.x;
float yLen=d1.y-d0.y;
float totalStep=max(abs(xLen),abs(yLen));
float xSpan=xLen/totalStep;
float ySpan=yLen/totalStep;
for(float i=0.;i<float(MAX_STEP);i++){
if(i>=totalStep) break;
vec2 xy=vec2(d0.x+i*xSpan,d0.y+i*ySpan);
if(xy.x<0.||xy.x>resolution.x||xy.y<0.||xy.y>resolution.y) break;
float s=length(xy-d0)/totalLen;
vec2 uv=xy/resolution;
float d = getDepth(uv);
float vZ = getViewZ( d );
if(-vZ>=cameraFar) continue;
float cW = cameraProjectionMatrix[2][3] * vZ+cameraProjectionMatrix[3][3];
vec3 vP=getViewPosition( uv, d, cW );
#ifdef PERSPECTIVE_CAMERA
// https://comp.nus.edu.sg/~lowkl/publications/lowk_persp_interp_techrep.pdf
float recipVPZ=1./viewPosition.z;
float viewReflectRayZ=1./(recipVPZ+s*(1./d1viewPosition.z-recipVPZ));
#else
float viewReflectRayZ=viewPosition.z+s*(d1viewPosition.z-viewPosition.z);
#endif
// if(viewReflectRayZ>vZ) continue; // will cause "npm run make-screenshot webgl_postprocessing_ssr" high probability hang.
// https://github.com/mrdoob/three.js/pull/21539#issuecomment-821061164
if(viewReflectRayZ<=vZ){
bool hit;
#ifdef INFINITE_THICK
hit=true;
#else
float away=pointToLineDistance(vP,viewPosition,d1viewPosition);
float minThickness;
vec2 xyNeighbor=xy;
xyNeighbor.x+=1.;
vec2 uvNeighbor=xyNeighbor/resolution;
vec3 vPNeighbor=getViewPosition(uvNeighbor,d,cW);
minThickness=vPNeighbor.x-vP.x;
minThickness*=3.;
float tk=max(minThickness,thickness);
hit=away<=tk;
#endif
if(hit){
vec3 vN=getViewNormal( uv );
if(dot(viewReflectDir,vN)>=0.) continue;
float distance=pointPlaneDistance(vP,viewPosition,viewNormal);
if(distance>maxDistance) break;
float op=opacity;
#ifdef DISTANCE_ATTENUATION
float ratio=1.-(distance/maxDistance);
float attenuation=ratio*ratio;
op=opacity*attenuation;
#endif
#ifdef FRESNEL
float fresnelCoe=(dot(viewIncidentDir,viewReflectDir)+1.)/2.;
op*=fresnelCoe;
#endif
vec4 reflectColor=texture2D(tDiffuse,uv);
gl_FragColor.xyz=reflectColor.xyz;
gl_FragColor.a=op;
break;
}
}
}
}
`
};
const SSRDepthShader = {
defines: {
'PERSPECTIVE_CAMERA': 1
},
uniforms: {
'tDepth': { value: null },
'cameraNear': { value: null },
'cameraFar': { value: null },
},
vertexShader: /* glsl */`
varying vec2 vUv;
void main() {
vUv = uv;
gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );
}
`,
fragmentShader: /* glsl */`
uniform sampler2D tDepth;
uniform float cameraNear;
uniform float cameraFar;
varying vec2 vUv;
#include <packing>
float getLinearDepth( const in vec2 uv ) {
#if PERSPECTIVE_CAMERA == 1
float fragCoordZ = texture2D( tDepth, uv ).x;
float viewZ = perspectiveDepthToViewZ( fragCoordZ, cameraNear, cameraFar );
return viewZToOrthographicDepth( viewZ, cameraNear, cameraFar );
#else
return texture2D( tDepth, uv ).x;
#endif
}
void main() {
float depth = getLinearDepth( vUv );
float d = 1.0 - depth;
// d=(d-.999)*1000.;
gl_FragColor = vec4( vec3( d ), 1.0 );
}
`
};
const SSRBlurShader = {
uniforms: {
'tDiffuse': { value: null },
'resolution': { value: new Vector2() },
'opacity': { value: .5 },
},
vertexShader: /* glsl */`
varying vec2 vUv;
void main() {
vUv = uv;
gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );
}
`,
fragmentShader: /* glsl */`
uniform sampler2D tDiffuse;
uniform vec2 resolution;
varying vec2 vUv;
void main() {
//reverse engineering from PhotoShop blur filter, then change coefficient
vec2 texelSize = ( 1.0 / resolution );
vec4 c=texture2D(tDiffuse,vUv);
vec2 offset;
offset=(vec2(-1,0))*texelSize;
vec4 cl=texture2D(tDiffuse,vUv+offset);
offset=(vec2(1,0))*texelSize;
vec4 cr=texture2D(tDiffuse,vUv+offset);
offset=(vec2(0,-1))*texelSize;
vec4 cb=texture2D(tDiffuse,vUv+offset);
offset=(vec2(0,1))*texelSize;
vec4 ct=texture2D(tDiffuse,vUv+offset);
// float coeCenter=.5;
// float coeSide=.125;
float coeCenter=.2;
float coeSide=.2;
float a=c.a*coeCenter+cl.a*coeSide+cr.a*coeSide+cb.a*coeSide+ct.a*coeSide;
vec3 rgb=(c.rgb*c.a*coeCenter+cl.rgb*cl.a*coeSide+cr.rgb*cr.a*coeSide+cb.rgb*cb.a*coeSide+ct.rgb*ct.a*coeSide)/a;
gl_FragColor=vec4(rgb,a);
}
`
};
export { SSRShader, SSRDepthShader, SSRBlurShader };
